Rapid Reduction in Heart Rate Using Hard Exhalation Diaphragmatic Breathing: Implications for Performance Management.  ROBERT M. STEIN (Lancaster, PA) and Tomeka Farrar (Mechanicsburg, PA).  Abstract: Diaphragmatic breathing or "belly breathing" is preferable to costal or chest breathing, in producing objective and subjective measures of relaxation. Practicing diaphragmatic breathing is not too difficult when already relaxed, but can be a challenge when one is in a high-pressure situation. High-pressure or "performance demand" situations present themselves with little opportunity to remove oneself for breathing practice. The current strategy emphasizes bodily movement and orally mediated hard exhalation to facilitate a rapid transition from costal to diaphragmatic breathing. Bodily movements include rotation of the shoulders, movement of the hips, bending at the knees and expansion/contraction of the torso. Oral movements include progressively more intense expulsion of air. Training involves increases in intensity, duration and speed over time. Data will be presented that demonstrate short-term reduction in heart rate that is associated with the transition from ordinary resting breathing to a more specific diaphragmatic breathing pattern.